docs: def identify_missing(self, df, check_start=True):
          """ Identify missing data.
  
          Parameters
          ----------
          df              : pd.DataFrame()
              Dataframe to check for missing data.
          check_start     : bool
              turns 0 to 1 for the first observation, to display the start of the data
          as the beginning of the missing data event
  
          Returns
          -------
          pd.DataFrame(), str
              dataframe where 1 indicates missing data and 0 indicates reported data,
          returns the column name generated from the MDAL Query
  
          """
  
          # Check start changes the first value of df to 1, when the data stream is initially missing
          # This allows the diff function to acknowledge the missing data
          data_missing = df.isnull() * 1
          col_name = str(data_missing.columns[0])
  
          # When there is no data stream at the beginning we change it to 1
          if check_start & data_missing[col_name][0] == 1:
              data_missing[col_name][0] = 0
  
          return data_missing, col_name